This invention relates to moulding articles of iced confectionery having a convex part, more particularly ice lollies quasi-ellipsoidal in shape.
Many small articles of ice confectionery with or without sticks are made by moulding in generally metallic moulds. These moulds may comprise one or more parts, and in the latter case, the various parts of the mould have to be separated during demoulding of the articles.
To make ice lollies having a convex part, for example quasi-ellipsoidal in shape, a rounded shape has to be given to the articles in the upper part of the mould. This operation cannot be carried out in one-piece metal moulds because one-piece metal moulds inevitably lead to the formation of a flat upper face dictated by the filling of the liquid ice composition. In addition, to demould the articles from these metal moulds, the mould cavity must not have a recessed upper part because otherwise, the article would not be demouldable.
In French Patent Application No. 2 535 581, an attempt was made to solve the problem of making so-called "non-demouldable" articles by using metal moulds in the form of two opposite, longitudinally hinged profiled half-shells. Held firmly against one another, the half-shells are filled with ice composition through an upper opening and, after the insertion of a stick, the half-shells thus filled are cooled in a cold-air freezing tunnel and then heated so that they may finally be opened to release the moulded articles.
Another method which is described in French Patent Application No. 2 502 467 comprises using half-shells which have a rounded profile in their inner part, but no external relief, and which fit longitudinally into a master mould with which they remain in contact. The master mould containing the two half-shells is cooled in a tank of refrigerating liquid (brine or glycol-containing water) which represents an advantage over the more expensive tunnel cooling. However, to demould the articles, the two half-shells have to be vertically removed from the master mould and then laterally separated to release the article. These operations involve the use of relatively complex and unwieldy mechanical extraction and demoulding tools.
Another process which is described in French Patent Application No. 2 265 283 comprises using moulds with thin flexible walls of rubber which can be turned inside out like gloves to demould the articles. However, this process involves certain risks where the relatively fragile flexible moulds are in contact with the cooling fluid.
Another process, the die-stamping process described for example in European Patent Application No. 39 511, uses a single mould. After demoulding, the lolly is deformed between two dies under the action of two press elements which form countermoulds. This process has the disadvantage that it does not produce particularly precise shapes, as reflected in particular in the presence of flash along the separation line between the two countermoulds.